Changes in dental arch measurements of young adults with normal occlusion--a longitudinal study.

This study evaluates the longitudinal changes in occlusal dimensions in young adults. The sample was composed of 27 individuals (13 male and 14 female individuals) who presented dental Class I and normal occlusion, according to the inclusion protocol. All teeth were present except for the third molars. The mean age of the subjects was 21 years and two months initially and 28 years and four months at the end of the observation period. The measurements collected in both arches were overbite, overjet, intercanine and intermolar distances, irregularity index, and perimeter. All measurements were taken from study dental casts by a calibrated operator, using a digital caliper. The paired t-test was used to evaluate the changes, using the difference between the initial and final mean measurements. Data indicated that the overbite increased 0.39 mm, the incisor irregularity increased 0.38 mm in the upper arch and 0.54 mm in the lower arch, and the arch perimeter decreased 0.67 mm in the upper arch and 0.71 mm in the lower arch (P > .05). The other measurements did not show significant changes. No sexual dimorphism was observed. It could be concluded that occlusal dimensions change throughout adult life. In the sample studied, changes were statistically significant for overbite, incisors irregularity, and arch perimeter after a mean period of seven years and two months. These changes can be observed in both sexes.